I'd like to write formulas and notes on my Droid X. All the styluses that I found have a thick end and don't simulate a pen, it's more like a finger. Does anyone know of any styluses with thinner or more accurate tips? Do pens from tablets like Lenovo work?

I have a Pogo Stylus which was originally meant for the iphone although I see they have an Android version now. It works ok, but I feel like I have to push down harder than I want to to get it to work. It is accurate, more so than my finger, however if I don't maintain enough pressure when drawing a line for example, there will be gaps in the line. I have a screen protector on and I've never tried it on the naked screen so this might be a factor. When all is said and done I don't use it very much so I can't provide a detailed review.

If you don't want to spend the money there are a number DIY capacitive tutorials that look pretty good. Some mimic the pogo design and others don't. Here are a few:

I remember seeing someone do tests on the accuracy of capacitive screens and in reality, they're terribly inaccurate. Unlike resistive screens, a stylus won't make much difference for you. I believe it was said that a fine stylus would provide just as much accuracy as using a hot dog.